Modified fibrous wollastonite and method of producing the same

ABSTRACT

A method of producing a modified fibrous wollastonite is provided. The method includes hydrothermally treating a fibrous wollastonite.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2017-104814, filed on May 26, 2017, the disclosure of which is herebyincorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a modified fibrous wollastonite and amethod of producing the modified fibrous wollastonite.

DESCRIPTION OF THE RELATED ART

Wollastonite is a fibrous natural mineral mainly composed of CaSiO₃. Asit is inexpensive, wollastonite is widely used, for example, as a resinreinforcing material. For example, Japanese Patent ApplicationPublication No. 2002-294070 describes a resin composition containingwollastonite for use as a material for a reflector to be included in alight emitting device. However, wollastonite, which is a naturalproduct, may contain impurity elements, such as iron (Fe), manganese(Mn), aluminum (Al), and carbon (C). These impurity elements can lower,for example, the dielectric properties of wollastonite. For example,Japanese Patent Application Publication No. Hei 9-255322 describes thatheat-treatment of a wollastonite reduces its variation in dielectricproperties.

SUMMARY

A modified fibrous wollastonite and a method of producing the modifiedfibrous wollastonite are provided. Surface analysis of the modifiedfibrous wollastonite by time-of-flight secondary ion mass spectrometry(TOF-SIMS) detects aluminum (Al), iron (Fe) and silicon (Si) where thedetection intensity ratio of Fe to Si is less than 0.13, and Al to Si isgreater than 0.03 to less than 1.08. The modified fibrous wollastoniteis produced by a method including hydrothermally treating a fibrouswollastonite.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of the structure of a light emitting deviceaccording to an embodiment of the present disclosure.

FIG. 2 is a cross-sectional view of the structure of the light emittingdevice according to the embodiment taken along the line IIA-IIA of FIG.1.

DETAILED DESCRIPTION

A resin composition containing a naturally occurring wollastonite maynot provide a sufficient reflectance when, for example, the resincomposition is used as a material for a reflector. One or more aspectsof the present disclosure are directed to a modified fibrouswollastonite with improved reflectance, and a method of producing themodified fibrous wollastonite.

A first aspect of the present disclosure is a method of producing amodified fibrous wollastonite. The method includes hydrothermallytreating a fibrous wollastonite.

A second aspect of the present disclosure is a fibrous wollastonite.Surface analysis of the fibrous wollastonite by TOF-SIMS detectsaluminum (Al), iron (Fe), and silicon (Si) where the detection intensityratio of Fe to Si is less than 0.13, and Al to Si is greater than 0.03to less than 1.08.

A third aspect of the present disclosure is a resin compositioncontaining the fibrous wollastonite and a resin.

As used herein, the term “step” means not only an independent step butalso a step which cannot be clearly distinguished from the other stepsbut that can achieve the intended object. For the amount of eachcomponent contained in a composition, when a plurality of substancescorresponding to the component are present in the composition, theamount of the component means the total amount of the correspondingsubstances present in the composition unless otherwise specified. Thepresent disclosure will now be described in accordance with theembodiments. However, the embodiments described below are mere examplesof the modified fibrous wollastonite and the method of producing thefibrous wollastonite for embodying the technical concept of the presentdisclosure, and the present disclosure is not limited to the modifiedfibrous wollastonite and the method of producing the fibrouswollastonite described below.

Method of Producing Modified Fibrous Wollastonite

The method of producing a modified fibrous wollastonite includeshydrothermally treating a fibrous wollastonite. Hydrothermally treatinga naturally occurring fibrous wollastonite improves reflectance of theresulting fibrous wollastonite.

A naturally occurring fibrous wollastonite contains impurities, such assodium (Na), potassium (K), iron (Fe), and aluminum (Al). Of theseimpurities, although Fe does not diffusively move to the surface by thehydrothermal treatment, for example, alkaline metals, such as Na and K,and Al seemingly diffusively move to the surface. The diffusively movedAl then seemingly forms a compound with Si (e.g., aluminum silicate) onthe surface, while Fe is less likely to diffusively move to the surfaceand form an Fe compound having high light absorption properties. Thisseemingly results in improved reflectance.

The improvement rate of the reflectance of the modified fibrouswollastonite at 550 nm is, for example 1% or more, preferably 2% ormore, more preferably 2.5% or more, and still more preferably 3% or morecompared with the reflectance before the hydrothermal treatment. Theupper limit of the improvement rate of the reflectance may be 20% orless. The improvement rate of the reflectance is determined as apercentage (%) of the value obtained by subtracting the reflectancebefore the modification from the reflectance after the modification, anddividing the obtained value by the reflectance before the modification.

The hydrothermal treatment is carried out by heating a fibrouswollastonite in the presence of water with pressure. For example, thehydrothermal treatment is carried out by heat-treating a mixturecontaining a fibrous wollastonite and water in a pressure-tight sealedcontainer.

The fibrous wollastonite that undergoes the hydrothermal treatment maybe any naturally occurring wollastonite mainly composed of CaSiO₃, andmay have been refined. The total amount of the impurity elements,exclusive of Ca, Si, and O, is, for example, 3% by mass or less, andpreferably 1% by mass or less. The fibrous wollastonite may be selectedfrom commercial products available from, for example, Kinsei Matec Co.,Ltd. The fibrous wollastonite may have an average fiber diameter of, forexample, from 0.1 μm to 30 μm, preferably from 0.1 μm to 15 μm, and morepreferably from 2 μm to 7 μm. The average fiber length is, for example,from 1 μm to 100 μm, preferably from 3 μm to 100 μm, and more preferablyfrom 20 μm to 50 μM. The ratio of the fiber length to the fiberdiameter, or the average aspect ratio, is for example 3 or more,preferably from 3 to 50, and more preferably from 5 to 30. The averagefiber diameter and the average fiber length of a fibrous wollastonitecan be obtained as an arithmetic mean value of 100000 particlesdetermined by observing images taken with a scanning electron microscope(SEM). The average particle diameter measured as Fisher Sub SieveSizer's No. (F.S.S.S.N) is, for example, from 0.5 μm to 10 μm.

Water used for the hydrothermal treatment is preferably purified water,such as ion exchanged water, distilled water, reverse osmosis water, orultrafiltration treated water.

The temperature of the hydrothermal treatment may be the boiling pointor above of water, and, for example, 120° C. or more, preferably 140° C.or more, 150° C. or more, 160° C. or more, or 170° C. or more. Also, thetemperature of the hydrothermal treatment may be, for example, 250° C.or less, and preferably 200° C. or less. Within this temperature range,the reflectance can further be improved.

The pressure to be applied in the hydrothermal treatment may be, forexample, a water vapor pressure in a pressure container to be used forthe hydrothermal treatment, and can be selected in accordance with theheating temperature. The pressure in the hydrothermal treatment may be,for example, 0.2 MPa or more, preferably 0.4 MPa or more, 0.6 MPa ormore, or 0.8 MPa or more. Also, the pressure in the hydrothermaltreatment may be, for example, 4 MPa or less, and preferably 1.6 MPa orless.

The duration of the hydrothermal treatment may be selected asappropriate in accordance with, for example, the heating temperature.The duration of the hydrothermal treatment may be, for example, 1 houror more, preferably 10 hours or more, or 24 hours or more. Also, theduration of the hydrothermal treatment may be, for example, 100 hours orless, preferably 72 hours or less, or 48 hours or less. Within thisduration range, the reflectance can be improved with further improvedproductivity.

The hydrothermal treatment may be carried out in the presence ofatmospheric air, or in an inert gas atmosphere, such as nitrogen, asappropriate.

The mixture containing a fibrous wollastonite and water that undergoesthe hydrothermal treatment may have a fibrous wollastonite content of,for example, 50% by mass or less, preferably 40% by mass or less, 30% bymass or less, or 25% by mass or less. Also, the mixture may have afibrous wollastonite content of, for example, 5% by mass or more, andpreferably 10% by mass or more. Within this range, the reflectance canbe improved with further improved productivity.

The fibrous wollastonite that undergoes the hydrothermal treatment mayhave a BET specific surface area of, for example, from 1 m²/g to 5 m²/g.The BET specific surface area is determined, for example, by drying thefibrous wollastonite at 250° C., and then measuring by the dynamicconstant-pressure method using nitrogen gas with an automatic specificsurface area measuring device, such as Gemini by Shimadzu.

The hydrothermal treatment may cause, for example, the impurities, suchas Al and K, contained in the fibrous wollastonite to move diffusivelyto the surface. This increases the total amount of, for example, Al andK on the surface compared with their amounts before the hydrothermaltreatment. The hydrothermal treatment is preferably carried out undersuch conditions that allow the total amount of, for example, Al and K onthe surface to be increased, for example, twice or more or five times ormore compared with the total amount of Al and K before the hydrothermaltreatment. Also, the hydrothermal treatment is preferably carried outunder such conditions that allow the total amount of, for example, Aland K on the surface to be increased, for example, 30 times or less,preferably 20 times or less compared with their amounts before thehydrothermal treatment. The analysis of the impurity elements on thesurface of the fibrous wollastonite can be carried out, for example, bylater described TOF-SIMS.

The method of producing the modified fibrous wollastonite may include,for example, the step of collecting the fibrous wollastonite throughsolid-liquid separation after the hydrothermal treatment, and the stepof drying at least a part of the adhered moisture as appropriate.

Fibrous Wollastonite

In the fibrous wollastonite according to the present embodiment,aluminum (Al), iron (Fe), and silicon (Si) are detected by surfaceanalysis by TOF-SIMS, and the detection intensity ratio of Fe to Si isless than 0.13, and Al to Si is greater than 0.03 to less than 1.08.Such a fibrous wollastonite is obtained by modifying, or for example,hydrothermally treating a naturally occurring fibrous wollastonite. Therespective detection intensity ratios of Al and Fe, which are containedin the fibrous wollastonite as impurities, to Si fall in a specificrange. This results in an improved reflectance of the fibrouswollastonite to light of, for example, from 320 nm to 730 nm.

The detection intensity ratio of Fe to Si (Fe/Si) in the fibrouswollastonite is less than 0.13, and is preferably 0.1 or less, and morepreferably 0.05 or less. The detection intensity ratio of Al to Si(Al/Si) is greater than 0.03 to less than 1.08, and is preferably 0.1 ormore, and more preferably 0.5 or more, and is also preferably 1.05 orless, and more preferably 1 or less. With the detection intensity ratioof Fe to Si and the detection intensity ratio of Al to Si in the aboveranges, the reflectance can be further improved.

The detection intensity ratio of Al to Fe (Al/Fe) in the fibrouswollastonite is, for example, 5 or more, preferably 10 or more, and morepreferably 20 or more. The upper limit of the detection intensity ratioof Al to Fe is, for example, 50, and preferably 40. With the detectionintensity ratio of Al to Fe in the above range, the reflectance can befurther improved.

The fibrous wollastonite may contain alkaline metals, such as Na and K,as impurity elements. When the fibrous wollastonite contains alkalinemetal, the detection intensity ratio of K to Si (K/Si) is, for example,0.7 or more, preferably 1 or more, and more preferably 2 or more. Theupper limit of the detection intensity ratio of K to Si is, for example,40 or less, preferably 20 or less, and more preferably 10 or less. Withthe detection intensity ratio of K to Si in the above range, thereflectance can be further improved.

The surface analysis of the fibrous wollastonite is carried out byTOF-SIMS. TOF-SIMS is carried out, for example, using TOF.SIMS 5-200 (byION-TOF) under the following conditions: primary ion source: Bi⁺,primary accelerated voltage: 30 kv, measurement area: 200 μm square, andprimary ion irradiation: 8.2×E10 ions/cm².

A fibrous wollastonite can contain a trace amount of an iron compound asimpurities. Through simple heat treatment, the iron compound seeminglychanges its oxidation state to an iron compound (e.g., α-Fe₂O₃) withhigh absorption of light of around 350 nm to 600 nm. However, throughhydrothermal treatment, the iron compound is less likely to change to aniron compound (e.g., α-Fe₂O₃) with high absorption of light of around350 inn to 600 nm. The oxidation state, when represented by the ratio ofoxygen atom (O) to Fe (0/Fe), of the iron compound as impurities afterthe hydrothermal treatment is for example greater than 0.5 to less than1.5, preferably from 0.7 to 1.3. The ratio of oxygen atom (O) to Fe inthe impurities is measured using a scanning electron microscope/energydispersive X-ray analyzer (SEM-EDX). Of the particles observed otherthan the fibrous wollastonite particles, the ratio of 0/Fe is measuredfor 5 or more particles, excluding the particles containing 10% by molor more of Si, or the particles not containing Fe. The average of themeasured values is defined as the oxidation state of the iron compoundas impurities. Specifically, the oxidation state is measured using anSEM-EDX (by Hitachi High-Technologies) under the condition ofacceleration voltage of 5 kV.

The iron compound contained as impurities after the hydrothermaltreatment includes at least an iron compound having magnetic properties.Examples of the iron compound having magnetic properties include, forexample, iron and magnetite (Fe₃O₄).

The fibrous wollastonite according to the present embodiment is mainlycomposed of CaSiO₃, and contains, as impurities, at least Fe and Al eachdetected at a specific intensity on the surface. The modifiedwollastonite is fibrous having an average fiber diameter of, forexample, from 0.1 μm to 30 μm, preferably from 0.1 μm to 15 μm, and morepreferably from 2 μm to 7 μm. The average fiber length is, for example,from 1 μm to 100 μm, preferably from 3 μm to 100 μm, and more preferablyfrom 20 μm to 50 μm. The average aspect ratio, or the ratio of fiberlength to fiber diameter, is, for example, 3 or more, preferably from 3to 50, and more preferably from 5 to 30.

Resin Composition

The resin composition contains a resin and the fibrous wollastonite inwhich Al, Fe, and Si are detected by surface analysis by TOF-SIMS, andthe detection intensity ratio of Fe to Si is less than 0.13, and Al toSi is greater than 0.03 to less than 1.08. The resin composition hashigh mechanical strength and improved light reflectance, and thus can beused, for example, as a material for a reflector, and is suitable as amaterial for forming a package for a light-emitting device.

The resin contained in the resin composition may be either thermoplasticor thermosetting. Examples of the thermoplastic resin include liquidcrystal polymers, aromatic polyamides, such as aliphatic polyamide andpolyphthalamide, and polyester, such as polybutylene terephthalate.Examples of the thermosetting resin include epoxy resin and siliconeresin.

The resin composition has a fibrous wollastonite content of, forexample, 5% by mass or more, preferably 10% by mass or more, and morepreferably 15% by mass or more, and also, for example, 70% by mass orless, preferably 40% by mass or less, and more preferably 20% by mass orless. The fibrous wollastonite has a high reflectance, and thus can becontained in a higher mass ratio than a naturally occurring fibrouswollastonite to further improve mechanical strength.

The resin composition may contain at least one of additives including aninorganic filler, such as titanium oxide, aluminum oxide, talc, silica,or zinc oxide; a flame retardant; a plasticizer; a diffusing agent; adye; a pigment; a releasing agent; an ultraviolet absorber; anantioxidant, and a heat stabilizer as appropriate. In particular, atleast one inorganic filler, such as titanium oxide or aluminum oxide, ispreferably contained. The average particle diameter of the inorganicfiller is, for example, from 0.08 μm to 10 μm, preferably from 0.1 μm to5 μm as Fisher Sub Sieve Sizer's No. (FSSSN). When an inorganic filleris contained in the composition, the filler content of the compositionis, for example, from 10% by mass to 60% by mass, and preferably from20% by mass to 50% by mass.

Light-Emitting Device

The light-emitting device includes a package formed from the resincomposition and including a bottom surface and walls forming a recess; alight-emitting element disposed on the bottom surface of the package;and a sealing member filled into the recess of the package to cover thelight-emitting element. The package formed from the resin compositionhas an improved mechanical strength. Further, the recess of the packagehaving an improved reflectance allows light from the light-emittingelement to be efficiently taken out.

The structure of the light-emitting device will now be described withreference to FIGS. 1 and 2. FIG. 1 is a perspective view of thestructure of a light-emitting device according to an embodiment of thepresent disclosure. FIG. 2 is a cross-sectional view of the structure ofthe light emitting device according to the embodiment taken along theline IIA-IIA of FIG. 1. In FIGS. 1 and 2, the observation direction isshown using xyz axes of coordinates for ease of explanation. In theelongated, substantially rectangular parallelepiped light-emittingdevice 1, the longitudinal direction is the direction of x-axis, thetransverse direction is the direction of y-axis, and the thicknessdirection is the direction of z-axis.

The light-emitting device 1 includes a package 2 having a recess 2 a, alight-emitting element 3 disposed on the bottom surface 2 b of therecess 2 a of the package 2, and a translucent sealing member 4 providedin the recess 2 a and sealing the light-emitting element 3. The package2 also includes a pair of lead electrodes 21 and a resin molded body 22holding the pair of lead electrodes 21. The light emitting device 1 hasan elongated, substantially rectangular parallelepiped outer shape, witha small thickness or dimension in the z-axis direction. In the lightemitting device 1, the end surface in the minus direction of the z-axisis the mounting surface. The recess 2 a is provided in a manner to openon the end surface side in the minus direction of the y-axis. Thus, thelight emitting device 1 is suitable for side view mounting in whichlight is emitted in a direction parallel to the mounting surface.

In the light-emitting device 1, the resin molded body 22 of the package2 is formed from a resin composition including a resin and the fibrouswollastonite in which aluminum (Al), iron (Fe), and silicon (Si) aredetected by surface analysis by TOF-SIMS, and the detection intensityratio of Fe to Si is less than 0.13, and Al to Si is greater than 0.03to less than 1.08.

The package 2 includes the pair of lead electrodes 21, and the resinmolded body 22 holding the pair of lead electrodes 21 in a manner toseparate the electrodes from each other. The package 2 has the recess 2a, which is open in a lateral direction with respect to the end surfacein the minus direction of the z-axis, or the mounting surface. Thus, thebottom surface 2 b of the recess 2 a is substantially perpendicular tothe mounting surface. The recess 2 a is defined by the bottom surface 2b, which includes the pair of lead electrodes 21 and the resin moldedbody 22, and side walls 22 a of the resin molded body 22. The side walls22 a has areas provided in the end surfaces in the z-axis direction, orthe vertical direction of the recess 2 a, and having a smaller thicknessthan the areas provided on the end surfaces in x-axis direction or thelateral direction.

The recess 2 a contains a light-emitting element 3, and the side walls22 a are provided in a manner to surround the light-emitting element 3.The inner surfaces of the side walls 22 a slope away from the bottomsurface 2 b side of the recess 2 a toward its opening at a predeterminedangle relative to the bottom surface 2 b. This allows light emittedlaterally from the light-emitting element 3 to be reflected from theside walls 22 a toward the opening to be taken out from the package 2.The resin molded body 22, which is formed from the resin compositioncontaining the fibrous wollastonite with an improved light reflectance,reflects light from the light-emitting element 3 to allow light to beefficiently taken out from the opening of the recess 2 a.

Along with the increasing demand for a downsized light-emitting device,its package is increasingly made thinner. Specifically, the resin moldedbody 22 surrounding the light-emitting element 3 desirably partly has athickness of, for example, 100 μm or less, or even 50 μm or less. Thepackage 2 has the recess 2 a with an oval opening, thus the outerdimension in the thickness direction of the package 2 can be downsizedwithout changing the dimensions of the recess 2 a by forming the sidewalls 22 a to be thinner in the longitudinal direction of the recess 2a. Thus, the light-emitting device 1 can be produced thinner.

The thin side walls 22 a, which are formed from the resin compositioncontaining the fibrous wollastonite, have a sufficient mechanicalstrength and an improved reflectance. Although the recess 2 of thepackage 2 according to the present embodiment has an oval opening, therecess 2 may have, for example, a circular, an elliptical, arectangular, or any other polygonal opening.

The light-emitting element 3 may include a substrate, such as sapphire,and a light-emitting layer formed on the substrate. For thelight-emitting layer, a semiconductor, such as GaAlN, ZnS, ZnSe, SiC,GaP, GaAlAs, AlN, InN, AlInGaP, InGaN, GaN, or, AlInGaN, may be used. Ofthese, a nitride compound semiconductor element having a peak emissionwavelength in the range of ultraviolet to visible light at shortwavelengths (360 nm to 550 nm) may be used.

The sealing member 4 is provided in the recess 2 a of the package 2 toseal, for example, the light-emitting element 3 disposed in the recess 2a, the lead electrodes 21, and a wire for electrically connecting thelight-emitting element 3 and the lead electrodes 21. Although thesealing member 4 may not be provided, the sealing member 4 can protectthe above members from deterioration due to moisture or gas, or damagedue to mechanical contact. Although the material usable as the sealingmember 4 are not particularly limited, the material is preferablytranslucent. Examples of the materials include resin materials, such assilicone resin and epoxy resin, and inorganic materials, such as glass.

The sealing member 4 may also contain a fluorescent substance forwavelength conversion of light from the light-emitting element 3, and aphoto-reflective substance for scattering light from the light-emittingelement 3. Examples of the photo-reflective substance may includeparticles of titanium oxide (TiO₂) and aluminum oxide (Al₂O₃). Thefluorescent substance may be any that absorbs light from thelight-emitting element 3, and converts the wavelength of the light to adifferent wavelength. For example, the fluorescent substance ispreferably at least one selected from the group consisting of, forexample, aluminum garnet-based fluorescent materials; nitride-basedfluorescent materials, oxynitride-based fluorescent materials, andsialon-based fluorescent materials that are mainly activated bylanthanoid elements, such as Eu and Ce; alkaline earth halogen apatitefluorescent materials, alkaline earth metal borate halogen fluorescentmaterials, alkaline earth metal aluminate fluorescent materials,alkaline earth metal silicates, alkaline earth metal sulfides, alkalineearth metal thiogallates, alkaline earth metal silicon nitrides andgermanates that are mainly activated by lanthanoid elements, such as Eu,and transition metal elements, such as Mn; rare earth aluminates andrare earth silicates that are mainly activated by lanthanoid elementssuch as Ce; and organic compounds and organic complex compounds that aremainly activated by lanthanoid elements, such as Eu.

EXAMPLES

The present invention will now be described in detail with reference toexamples, but the present invention is not limited to these examples.

Example 1

10 g of a fibrous wollastonite (Wollastonite SH-1800 by Kinsei Matec,average fiber diameter: 3.5 average fiber length: 28 μm) and 70 ml ofpure water were charged into a Teflon vessel (0.1 L), and sealed in aclosed container. The whole container was hydrothermally treated at 170°C. for 60 hours, then solid-liquid separated, and dried at 105° C. toobtain a hydrothermally treated wollastonite.

Comparative Example 1

10 g of a fibrous wollastonite (SH-1800) was heat-treated in an aluminacrucible at 800° C. for 2 hours to obtain a heat-treated wollastonite.

TOF-SIMS Evaluation

The hydrothermally treated wollastonite and the heat-treatedwollastonite obtained above, and an untreated wollastonite (SH-1800)were subjected to surface analysis by TOF-SIMS (TOF.SIMS 5-200 byION-TOF). The measurement conditions were as follows: primary ionsource: Br, primary acceleration voltage: 30 kv, measurement area: 200μm square, and primary ion irradiation: 8.2×E 10 ions/cm². Therespective detection intensity ratios of Al to Si, Fe to Si, and K to Siwere determined. The results are shown in Table 1.

Reflectance Evaluation

For each of the hydrothermally treated wollastonite, the heat-treatedwollastonite, and the untreated wollastonite, the reflectances at 450nm, at 550 nm, and at 650 nm were measured with a phosphor quantumefficiency spectrophotometer, QE-2000 (by Otsuka Electronics). Thedifference in reflectance between the hydrothermally treatedwollastonite and the untreated wollastonite, and the difference inreflectance between the heat-treated wollastonite and the untreatedwollastonite were each divided by the reflectance of the untreatedwollastonite to obtain respective reflectance improvement rates (%). Theresults are shown in Table 1.

SEM-EDX Evaluation

For each of the hydrothermally treated wollastonite, the heat-treatedwollastonite, and the untreated wollastonite, the oxidation state of Fewas evaluated under the measurement condition of acceleration voltage: 5kV using an SEM-EDX (by Hitachi High-Technologies). Fe oxidation degreewas obtained as the ratio of O to Fe (O/Fe). Of the particles observedother than the fibrous wollastonite particles, the ratio of oxygen atom(O) to Fe was measured for 5 or more particles excluding the particlescontaining 10% by mol or more of Si, or the particles not containing Fe,using an SEM-EDX, and an average value was calculated. The results areshown in Table 2.

Magnetism Evaluation

The hydrothermally treated wollastonite, the heat-treated wollastonite,and the untreated wollastonite were each put into pure water to obtainslurry. Into each slurry, Nd magnet was charged, and stirred for 30 min.The presence of attachment was visually inspected. The results are shownin Table 2.

TABLE 1 Reflectance improvement TOF-SIMS rate (%) Treatment Al Fe K 450nm 550 nm 650 nm Hydrothermal 0.30 0.01 4.24 2.5 3.4 3.7 treatment Heattreatment 1.08 0.13 45.85 −10.8 −1.5 1.2 No treatment 0.03 0.02 0.67 — ——

Table 1 shows that the wollastonite through the hydrothermal treatmenthas an improved reflectance compared with the heat-treated product andthe untreated product at every wavelength. Although the heated productshows an improved reflectance compared with the untreated product in therange of above 550 nm to 650 nm, the reflectance is lower in the rangeof from 450 nm to 550 nm. The surface analysis by TOF-SIMS of thehydrothermally treated wollastonite shows that the detection intensityratio of Fe to Si is less than 0.13, and the detection intensity ratioof Al to Si is greater than 0.03 to less than 1.08. These results showthat the wollastonite through the hydrothermal treatment allowed more Alcontained inside the wollastonite to diffusively move to the surface ofthe wollastonite than the untreated product, and less Fe containedinside to diffusively move to the surface than the heated product. Thisseemingly results in improved reflectance of the hydrothermally treatedwollastonite.

TABLE 2 Fe oxidation Magnetism Treatment degree evaluation Hydrothermaltreatment 1.0 Black powder Heat treatment 1.7 None No treatment 0.5Black powder

Table 2 shows that the iron compound contained as impurities in thehydrothermally treated wollastonite has a lower Fe oxidation degree thanthe heated product, and has magnetic properties, and thus differs fromthe iron compound contained as impurities in the heated product.

Example 2-1

10 g of a fibrous wollastonite (SH-1800; a product from a different lotfrom Example 1) and 70 ml of pure water were charged into a Teflonvessel (0.1 L), and sealed in a closed container. The whole containerwas hydrothermally treated at 140° C. for 24 hours, solid-liquidseparated, and dried at 105° C. to obtain a hydrothermally treatedwollastonite. Table 3 shows the reflectance improvement rates.Concentrations shown in Table 3 each indicate the percent by mass (%) ofthe fibrous wollastonite in each hydrothermally treated product or eachheat-treated product.

Examples 2-2 and 2-3

Hydrothermally treated wollastonites of Examples 2-2 and 2-3 wereobtained in the same manner as in Example 2-1 except that thetemperature of hydrothermal treatment was changed to 170° C. and 200°C., respectively. The reflectance improvement rates are shown in Table3.

Comparative Examples 2-1 and 2-2

For each of Comparative Examples 2-1 and 2-2, 20 g of a fibrouswollastonite (SH-1800; a product from the same lot of Example 2-1) and140 ml of pure water were charged into a beaker, and stirred at 15° C.or 70° C. for 24 hours, solid-liquid separated at 105° C., and dried toobtain a water-treated wollastonite. The reflectance improvement ratesare shown in Table 3.

Examples 3-1 to 3-4

Hydrothermally treated wollastonites of Examples 3-1 to 3-4 were eachobtained in the same manner as in Example 2-1 except that thetemperature of the hydrothermal treatment was changed to 170° C., andthe duration of the hydrothermal treatment was changed to 10 hours, 34hours, 60 hours, and 70 hours, respectively. The reflectance improvementrates are shown in Table 3.

Example 4-1

Hydrothermally treated wollastonite of Example 4-1 was obtained in thesame manner as in Example 3-3 except that 5 g of a fibrous wollastonite(SH-1800) and 75 ml of pure water were used, and that the concentrationof fibrous wollastonite was changed to 6.3% by mass. The reflectanceimprovement rate is shown in Table 3.

Example 4-2

Hydrothermally treated wollastonite of Example 4-2 was obtained in thesame manner as in Example 3-3 except that 20 g of a fibrous wollastonite(SH-1800) and 60 ml of pure water were used, and that the concentrationof fibrous wollastonite was changed to 25.0% by mass. The reflectanceimprovement rate is shown in Table 3.

Example 4-3

Hydrothermally treated wollastonite of Example 4-3 was obtained in thesame manner as in Example 3-3 except that 30 g of a fibrous wollastonite(SH-1800) and 50 ml of pure water were used, and that the concentrationof fibrous wollastonite was changed to 37.5% by mass. The reflectanceimprovement rate is shown in Table 3.

TABLE 3 Hydrothermal treatment conditions Reflectance improvementTemperature Duration Concentration rate (%) (° C.) (hr) (% by mass) 450nm 550 nm 650 nm Example 2-1 140 24 12.5 2.4 2.8 3.0 Example 2-2 170 3.24.0 4.2 Example 2-3 200 3.1 3.5 4.2 Comparative 15 −0.1 −0.2 −0.2Example 2-1 Comparative 70 0.1 −0.2 −0.3 Example 2-2 Example 3-1 170 1012.5 2.9 3.3 3.2 Example 2-2 24 3.2 4.0 4.2 Example 3-2 34 3.4 4.1 4.2Example 3-3 60 3.2 4.0 4.2 Example 3-4 70 3.1 3.9 4.1 Example 4-1 170 606.3 2.2 3.3 3.4 Example 3-3 12.5 3.2 4.0 4.2 Example 4-2 25 2.5 3.6 3.6Example 4-3 37.5 2.1 2.8 2.7

Table 3 indicates that hydrothermally treating a fibrous wollastoniteimproves its reflectance.

Example 5

The hydrothermally treated wollastonite obtained in Example 1, titaniumoxide (CR-90-2 by Ishihara Sangyo, average particle diameter: 0.45 μm),and polyamide resin (ARLEN C2000 by Mitsui Chemicals) were melt andkneaded to have a mass ratio of 15:40:45 at a temperature of 320° C.,which is equal to or higher than the melting point of polyamide resin,and molded by extrusion to prepare Resin Composition Pellet 1.

Comparative Example 3

Resin Composition Pellet C1 was prepared in the same manner as inExample 5 except that an untreated fibrous wollastonite (SH-1800) wasused.

Evaluation of Resin Compositions

From each of Resin Composition Pellets 1 and C1, a molded body having athickness of 4 mm was prepared. For each of the molded body, reflectanceat 560 nm was measured using QE-2000 by Otsuka Electronics.

Comparison of the reflectances revealed that the molded body preparedfrom Resin Composition Pellet 1 has a 1.2% higher reflectance than themolded body prepared from Resin Composition Pellet C1.

Light-Emitting Device

Packages were prepared by injection-molding Resin Composition Pellets 1and C1, and light-emitting devices like the one shown in FIG. 1 wereproduced using the same light-emitting element, the same sealing resin,and the same fluorescent substance. The total luminous flux of lightemitted from each light-emitting device with the light-emitting elementbeing activated was evaluated with a total luminous flux measuringmachine including an integrating sphere. Comparison of the luminousfluxes revealed that the light-emitting device produced from ResinComposition Pellet 1 has 0.7% higher luminous flux than thelight-emitting device produced from Resin Composition Pellet C1.

It is to be understood that although the present invention has beendescribed with regard to preferred embodiments thereof, various otherembodiments and variants may occur to those skilled in the art, whichare within the scope and spirit of the invention, and such otherembodiments and variants are intended to be covered by the followingclaims.

Although the present disclosure has been described with reference toseveral exemplary embodiments, it is to be understood that the wordsthat have been used are words of description and illustration, ratherthan words of limitation. Changes may be made within the purview of theappended claims, as presently stated and as amended, without departingfrom the scope and spirit of the disclosure in its aspects. Although thedisclosure has been described with reference to particular examples,means, and embodiments, the disclosure may be not intended to be limitedto the particulars disclosed; rather the disclosure extends to allfunctionally equivalent structures, methods, and uses such as are withinthe scope of the appended claims.

One or more examples or embodiments of the disclosure may be referred toherein, individually and/or collectively, by the term “disclosure”merely for convenience and without intending to voluntarily limit thescope of this application to any particular disclosure or inventiveconcept. Moreover, although specific examples and embodiments have beenillustrated and described herein, it should be appreciated that anysubsequent arrangement designed to achieve the same or similar purposemay be substituted for the specific examples or embodiments shown. Thisdisclosure may be intended to cover any and all subsequent adaptationsor variations of various examples and embodiments. Combinations of theabove examples and embodiments, and other examples and embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the description.

In addition, in the foregoing Detailed Description, various features maybe grouped together or described in a single embodiment for the purposeof streamlining the disclosure. This disclosure may be not to beinterpreted as reflecting an intention that the claimed embodimentsrequire more features than are expressly recited in each claim. Rather,as the following claims reflect, inventive subject matter may bedirected to less than all of the features of any of the disclosedembodiments. Thus, the following claims are incorporated into theDetailed Description, with each claim standing on its own as definingseparately claimed subject matter.

The above disclosed subject matter shall be considered illustrative, andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments which fall within thetrue spirit and scope of the present disclosure. Thus, to the maximumextent allowed by law, the scope of the present disclosure may bedetermined by the broadest permissible interpretation of the followingclaims and their equivalents, and shall not be restricted or limited bythe foregoing detailed description.

All publications, patent applications, and technical standards mentionedin this specification are herein incorporated by reference to the sameextent as if each individual publication, patent application, ortechnical standard was specifically and individually indicated to beincorporated by reference.

What is claimed is:
 1. A method of producing a modified fibrouswollastonite, the method comprising: hydrothermal treatment of a fibrouswollastonite.
 2. The method according to claim 1, wherein thehydrothermal treatment is carried out at a temperature of above 100° C.to 250° C.
 3. The method according to claim 1, wherein the hydrothermaltreatment is carried out under a pressure of 4 MPa or less.
 4. Themethod according to claim 1, wherein the hydrothermal treatment iscarried out in a time period of from 1 hour to 100 hours.
 5. The methodaccording to claim 1, wherein the fibrous wollastonite content in thehydrothermal treatment is 40% by mass or less.
 6. The method accordingto claim 2, wherein the hydrothermal treatment is carried out under apressure of 4 MPa or less.
 7. The method according to claim 2, whereinthe hydrothermal treatment is carried out in a time period of from 1hour to 100 hours.
 8. The method according to claim 2, wherein thefibrous wollastonite content in the hydrothermal treatment is 40% bymass or less.
 9. The method according to claim 3, wherein thehydrothermal treatment is carried out in a time period of from 1 hour to100 hours.
 10. The method according to claim 3, wherein the fibrouswollastonite content in the hydrothermal treatment is 40% by mass orless.
 11. The method according to claim 4, wherein the fibrouswollastonite content in the hydrothermal treatment is 40% by mass orless.
 12. The method according to claim 6, wherein the hydrothermaltreatment is carried out in a time period of from 1 hour to 100 hours.13. The method according to claim 6, wherein the fibrous wollastonitecontent in the hydrothermal treatment is 40% by mass or less.
 14. Themethod according to claim 7, wherein the fibrous wollastonite content inthe hydrothermal treatment is 40% by mass or less.
 15. The methodaccording to claim 9, wherein the fibrous wollastonite content in thehydrothermal treatment is 40% by mass or less.
 16. The method accordingto claim 12, wherein the fibrous wollastonite content in thehydrothermal treatment is 40% by mass or less.
 17. A fibrouswollastonite in which Al, Fe, and Si are detected by surface analysis bytime-of-flight secondary ion mass spectrometry, with a detectionintensity ratio of Fe to Si being less than 0.13, and a detectionintensity ratio of Al to Si being greater than 0.03 to less than 1.08.18. A resin composition comprising the fibrous wollastonite according toclaim 17, and a resin.